Did your vet exam Emma and do any tests?
Could she have gotten into anything she shouldn't?
Has she drunk any water from ponds or birdbaths?
What other dog food brands did you try previously?
Have long has she been on the current food?
You'll probably get a lot of comments here on the Beneful as it is rather low on the quality status.
I, personally, am not near any stores that sell the high-end foods and they would be out of m;y budget with 3 dogs. I have had very good success feeding my crew Iams Pro-Active Health in the small kibble. Firm poop all around. It's reasonably priced at Walmart.
Regarding the bag you have, is there a phone number on it for consumer questions? Is that where you checked about any bad batches? Did this bag smell any different to you?
Check Emma for dehydration. Hope she feels better soon.